Fix hole handling, and ensure smi representation is handled properly

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5447 matching lines @@
     SetOperandAt(1, key);
     SetOperandAt(2, dependency != NULL ? dependency : obj);
 
     if (!is_external()) {
       // I can detect the case between storing double (holey and fast) and
       // smi/object by looking at elements_kind_.
       ASSERT(IsFastSmiOrObjectElementsKind(elements_kind) ||
              IsFastDoubleElementsKind(elements_kind));
 
       if (IsFastSmiOrObjectElementsKind(elements_kind)) {
-        if (IsFastSmiElementsKind(elements_kind)) {
+        if (IsFastSmiElementsKind(elements_kind) &&
+            (!IsHoleyElementsKind(elements_kind) ||
+             mode == NEVER_RETURN_HOLE)) {
           set_type(HType::Smi());
           set_representation(Representation::Smi());
         } else {
           set_representation(Representation::Tagged());
         }
 
         SetGVNFlag(kDependsOnArrayElements);
       } else {
         set_representation(Representation::Double());
         SetGVNFlag(kDependsOnDoubleArrayElements);
@@ skipping 288 matching lines @@
     // EXTERNAL_{UNSIGNED_,}{BYTE,SHORT,INT}_ELEMENTS are truncating.
     if (elements_kind >= EXTERNAL_BYTE_ELEMENTS &&
         elements_kind <= EXTERNAL_UNSIGNED_INT_ELEMENTS) {
       SetFlag(kTruncatingToInt32);
     }
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
     // kind_fast:       tagged[int32] = tagged
     // kind_double:     tagged[int32] = double
+    // kind_smi   :     tagged[int32] = smi
     // kind_external: external[int32] = (double | int32)
     if (index == 0) {
       return is_external() ? Representation::External()
                            : Representation::Tagged();
     } else if (index == 1) {
       return ArrayInstructionInterface::KeyedAccessIndexRequirement(
           OperandAt(1)->representation());
     }
 
     ASSERT_EQ(index, 2);
     if (IsDoubleOrFloatElementsKind(elements_kind())) {
       return Representation::Double();
     }
 
     if (IsFastSmiElementsKind(elements_kind())) {
       return Representation::Smi();
     }
 
     return is_external() ? Representation::Integer32()
                          : Representation::Tagged();
   }
 
   bool is_external() const {
     return IsExternalArrayElementsKind(elements_kind());
   }
 
   virtual Representation observed_input_representation(int index) {
     if (index < 2) return RequiredInputRepresentation(index);
+    if (IsFastSmiElementsKind(elements_kind())) {
+      return Representation::Smi();
+    }
     if (IsDoubleOrFloatElementsKind(elements_kind())) {
       return Representation::Double();
     }
     if (is_external()) {
       return Representation::Integer32();
     }
     // For fast object elements kinds, don't assume anything.
     return Representation::None();
   }
 
@@ skipping 698 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_